Electrical resistivity and passive acoustic techniques have been used to remotely monitor the location of the reaction zone in an in situ coal gasification experiment conducted near Hanna, Wyoming. Thermal measurements were made to provide diagnostic information, to aid in understanding the process, and to evaluate the effectiveness of the remote techniques. From a comparison of field resistivity data and model calculations the path of the reaction zone was determined. Source locations in the overburden for acoustical events during gasification are associated with subsidence over the gasified area. The feasibility of these remote techniques to monitor in situ coal gasification has been demonstrated.